In recent years, a secondary battery, which can be repeatedly charged and discharged, has been widely used as an energy source for wireless mobile devices. In addition, the secondary battery has attracted considerable attention as an energy source for electric vehicles and hybrid electric vehicles, which have been developed to solve problems, such as air pollution, caused by existing gasoline and diesel vehicles that use fossil fuels. As a result, kinds of applications using the secondary battery are being increased owing to advantages of the secondary battery, and hereafter the secondary battery is expected to be applied to more applications and products than now.
Based on the construction of electrodes and an electrolyte, the secondary battery may be classified as a lithium ion battery, a lithium ion polymer battery, or a lithium polymer battery. In particular, the lithium ion polymer battery has been increasingly used because the lithium ion polymer battery has a low possibility of electrolyte leakage and can be easily manufactured.
Based on the shape of a battery case, the secondary battery may also be classified as a cylindrical battery having an electrode assembly mounted in a cylindrical metal can, a prismatic battery having an electrode assembly mounted in a prismatic metal can, or a pouch-shaped battery having an electrode assembly mounted in a pouch-shaped case made of an aluminum laminate sheet.
The secondary battery is being widely used as an energy source for diverse electronic products as well as various kinds of mobile devices. However, various kinds of combustible materials are contained in the secondary battery. As a result, the lithium secondary battery may overheat or explode due to the overcharge of the secondary battery, the overcurrent in the secondary battery, or other external physical impact applied to the secondary battery.
For this reason, the secondary battery is provided with a safety system, such as a protection circuit for interrupting electric current when the secondary battery is overcharged or overdischarged or when overcurrent flows in the secondary battery, a positive temperature coefficient (PTC) element whose resistance greatly increases so as to interrupt electric current when the temperature of the secondary battery increases, or a safety vent for interrupting electric current or exhausting gas when pressure increases due to generation of the gas. Meanwhile, a multi-cell type middle or large-sized battery pack, which is configured to have a multi-cell structure in which a plurality of battery modules is combined, is provided with a safety system, such as a fuse, a bimetal, or a battery management system (BMS), for protecting battery cells from overcharge, overdischarge, or overcurrent.
Voltage sensing terminals are connected to the BMS, which is one of the above-described safety systems, via wires so as to detect voltages of battery cells or unit modules.
FIG. 1 is a typical view showing a conventional battery module having a structure in which a BMS is connected to voltage sensing terminals via wires.
Referring to FIG. 1, a battery module 10 is configured to have a structure in which a plurality of battery cells 11 is arranged in the state in which the battery cells 11 are adjacent to each other laterally, frames 12 are mounted to opposite ends of the battery cells 11, and a BMS 13 is located at the upper side of one end of the battery cells 11.
The BMS 13 is connected to voltage sensing terminals 14 via wires 15. The battery cells 11 are connected to each other in series. It is required for the BMS 13 to monitor voltages of the respective battery cells 11. For this reason, it is necessary for the number of voltage sensing terminals 14 to be equal to the number of battery cells. In addition, it is necessary for the number of wires 15 to be equal to the number of battery cells. In this structure, the voltage sensing terminals 14 and the wires 15 are manually soldered, with the result that the manufacturing process is complicated, and the wires are arranged complicatedly, whereby the structure of the battery module becomes complicated.
Therefore, there is a high necessary for a battery module that is capable of solving the above problems.